The exploration and production of hydrocarbons require the use of drilling systems that include tubulars such as drill pipes, casings, and other threadedly connected elements used in the well structures. The connection of “strings” of joined tubulars, or drill strings, is typically used to drill a wellbore and with regard to casing prevent collapse of the wellbore after drilling. These tubulars are normally assembled in groups of two or more commonly known as “stands” to be vertically stored in the derrick or mast.
On a drilling rig, the drill string may be assembled in the derrick or mast. The drill string may be run downhole and into the wellbore. The drill string may be used to transmit rotational power to the drill bit located at its lower end. The drill string may also be used to transmit drilling fluid, commonly known as mud, down through the internal bore in the drill string. The mud exits at or near the drill bit and then circulates back up the well annulus between the drill string and the well bore. The drill pipe string may also run casing, a liner, or a landing string downhole. The drill string may also be used for work-over activity of a hydrocarbon well. Drill strings are only limited in length by material limitations, which is constantly being improved to allow for drilling deeper and having longer deviated or horizontal drilled wells.
The drill string is comprised of tubulars threaded and connected together by their threaded ends. A joint or segment of a drill pipe may vary in length. A joint or segment of drill pipe is comprised of a female connection, known as the “box” and a male section known as the “pin”. The box end is internally threaded and adapted to receive the pin end member of another drill pipe joint, which has external threads. Building the joints of drill pipe may be conducted by interconnecting the threads to make up the drill string. The drill string may be securely made up to, for example, prevent leakage, wobbling, or unscrewing, resulting in a lost well. Typically, power tongs or automated roughnecks are used to transmit sufficient torque to the pipe joints to ensure that the pin is securely tightened to the box. The amount of torque required to securely tighten the tubulars is known as make-up torque. The amount of torque required depends in part on the specific frictional properties of the threaded connections. The ability to impart higher friction coefficient may decrease the amount of torque to be transmitted and greatly reduces the instances of tool joints unscrewing. A lower friction coefficient may allow more torque to be transmitted which may result in too much torque applied when making up the joints. Excessive torque could stretch or burst the box member or crack or break the pin member.
Anti-seizing material known in the industry as “pipe dope” may be applied to the threaded connections of the joints to maintain a high coefficient of friction. The dope may assist with make-up and break-out operations by reducing required torque.
Typically, rig personnel manually apply pipe dope to the threaded pipe connections. This operation may be time consuming and dangerous for the rig personnel.